<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>组合选择器</title>
    <style>
        div,span,p{
            color: yellow;
        }

        .c1,#outer{
            color:teal;
        }




    </style>
</head>

<body>
    <div class="c1">div</div>
    <span class="c2">span</span>
    <p id="outer">p</p>
</body>

</html>